Keto Peanut Butter Mug Cake


5 from 66 votes
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This peanut butter mug cake is made with just 3 ingredients and is completely keto and flourless! Ready in under a minute and full of peanut butter flavor, it’s a delicious low carb and sugar free dessert. 

keto peanut butter mug cake

3 Ingredient Keto Mug Cake

When it comes to keto mug cake recipes, my favorites include a pumpkin mug cake, gingerbread mug cake, and this keto peanut butter mug cake.

Ever since starting a keto diet, peanut butter soon became one of my most used ingredients. Whether it be using it in recipes, snacking on it between meals, or slathering a piece of keto bread with it, it’s safe to say I eat it every single day. 

FACT– I eat peanut butter balls every single day. 

Recently, I’ve been ending my day with various single-serving desserts. Mug cakes have always been my go-to. Recently, I’ve been obsessed with this peanut butter version. 

Unlike most mug cakes out there, this one only needs 3 ingredients! No grains, no flour, and no sugar needed, it’s a low carb way to satisfy my sweet tooth! This mug cake takes less than a minute to make, and is also naturally gluten free!

Ingredients for this recipe

  • Peanut butter– Make sure the peanut butter you use has a smooth and drippy texture. As this is a keto mug cake, you want to be using sugar free peanut butter. 
  • Granulated sweetener– Either monk fruit sweetener or erythritol can be used. I prefer erythritol as for microwave desserts, as it has a better flavor. 
  • Egg– Room temperature egg.
  • Baking powder– Optional, but gives the mug cake that extra fluffiness. 

How do you make a peanut butter mug cake?

Start by whisking together all your ingredients in a small mixing bowl, until a batter remains. Transfer your batter into a microwave safe bowl, ramekin, or mug. Microwave for 45 seconds, to a minute. Remove from the microwave and let sit for a minute, before enjoying it.


Tips to make the best mug cake

  • If you’d like to make this mug cake in the oven, simply bake it at 180C/350F for 8-10 minutes. Be sure the ramekin you use for it is oven safe. 
  • Oven makes and models are different. Your mug cake may take longer than 45 seconds to make. 
  • Do not overbake the mug cake. This is a flourless dessert, so the cooking time is greatly reduced. 
  • You can either use 1 or 2 tablespoons of sweetener. I stick to one tablespoon, as I find it plenty sweet as it is. 
  • If you have a microwave safe cereal bowl, you can use that instead of a ramekin. This is a better option if you are worried that there may be overflow. 

Flavor and dietary Variations

  • Peanut Butter Chocolate Chip– As pictured. Add 1-2 teaspoons of keto chocolate chips to the batter and on top of the mug cake. 
  • Chocolate Peanut Butter– Add 1-2 tablespoons of cocoa powder to the batter. 
  • Peanut butter and jelly– Swirl through 1-2 teaspoons of your favorite jelly or jam into it. 
  • Vegan peanut butter mug cake– Replace the egg with 1/4 cup all purpose flour and 1/4 cup plant based milk. 
  • Paleo peanut butter mug cake– Replace the peanut butter with either almond butter or cashew butter.

peanut butter mug cake

More delicious mug cakes to try

3 ingredient keto mug cake

Peanut Butter Mug Cake (3 Ingredients!)

5 from 66 votes
This keto peanut butter mug cake is made with just 3 ingredients and takes less than a minute to make! Fluffy and full of peanut butter flavor, it's your low carb and sugar free dessert for one!
Servings: 1 mug cake
Prep: 1 minute
Cook: 1 minute
Total: 2 minutes



  • In a small mixing bowl, add all your ingredients and whisk together, until combined.
  • Transfer your mug cake batter into a greased microwave-safe ramekin or cereal bowl. Microwave for 45 seconds-1 minute. Remove from the microwave and let sit for a minute, before eating.

Oven Instructions

  • Preheat the oven to 180C/350F. Grease an oven-safe ramekin (6-8 inches) with oil. Make the batter before transferring to the ramekin. Bake for 8-10 minutes.


* Erythritol, monk fruit sweetener, or keto brown sugar can all be used. Use the full 2 tablespoons if you prefer a sweeter mug cake. 


Serving: 1mug cakeCalories: 355kcalCarbohydrates: 10gProtein: 18gFat: 29gSodium: 535mgPotassium: 381mgFiber: 3gVitamin A: 270IUCalcium: 184mgIron: 2mgNET CARBS: 7g
Course: Dessert
Cuisine: American
Author: Arman
Tried this recipe?Give us a shout at @thebigmansworld or tag #thebigmansworld!

Disclosure: This post may contain affiliate links. I may earn a small commission for my endorsement, recommendation, testimonial, and/or link to any products or services from this website.

Arman Liew

I’m a two time cookbook author, photographer, and writer, and passionate about creating easy and healthier recipes. I believe you don’t need to be experienced in the kitchen to make good food using simple ingredients that most importantly, taste delicious.

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Recipe Rating


  1. 5 stars
    can’t wait to try these. Not only do they look delicious, but the ingredients are also inexpensive and fast to prepare and cook.
    This way I’m saving money and these days every little bit counts.
    Thank you so much
    Great Grandma on Social Security